[OpenMP] Fix dynamic schedule assertion failure on AArch64

[Nawrin]

Summary

This patch fixes assertion failure for dynamic schedule with 8 byte induction variable. It checks the steal lock of selected victim and if the lock is not initialized then pick a different victim to steal from.

The bug report: https://github.com/llvm/llvm-project/issues/54422#issuecomment-1274020428

[AndreyChurbanov]

openmp/runtime/src/kmp_dispatch.cpp

1293

This change fights with the consequence of the problem, not with the root cause. IMHO, the better fix would be to change

if (KMP_ATOMIC_LD_RLX(&v->steal_flag) != READY ||

to

if (KMP_ATOMIC_LD_ACQ(&v->steal_flag) != READY ||

Then the acquire load would synchronize with release store at buffer initialization, that should prevent the steal_lock pointer to ever be NULL here.

[AndreyChurbanov]

LGTM.

This patch fixes the issue reported in https://github.com/llvm/llvm-project/issues/54422 for me.